Neon tube and method of making the same



A. P. TALLMAN NEON TUBE AND METHOD OF MAKING THE SAME Filed Dec. 17,1934 PatentedDec. 10, 1935 PATENT OFFICE NEON TUBE AND METHOD OF MAKINGTHE SAME

Allen P. Tallman, Toledo, Ohio V Application December 17, 1934, SerialNo. 757,943

6Claims.

This invention relates to an improvement in ary to use tubes containingneon, argon krypton or the like rendered luminescent by high 10 tensioncurrent. The glass tubes employed for this purpose are bent into theshape of various letters, figures and designs and lend themselves veryreadily to such shaping.

The light emitted from the tube escapes in a1 directions but ordinarilythe sign is viewed from only one side. If the tube'is mounted in frontof a board or backing as is generally the case,

the light emitted in the direction of the board is partly absorbed andpartly reflected by the backing boardQand in neither case does it haveany beneficial efiect from the standpoint of rendering the sign visible.This invention has for its object the reflection of a large part of thelight rays from the back of the tube so that they may be directed to theside from which the sign will be seen, and also contemplates theabsorption of any rays which are not reflected so that they will notilluminate the background. Accordingly, the lighted tubes stand out moredisw tinctly both because of the reflected light and because of therelatively dark background. Details and further features of theinvention will appear as the description proceeds.

In the accompanying drawing forming a. part of this specification,Figure l is a section through a tube showing one form of the inventionand also showing a portion of a backing behind the tube. Figure 2 is aview similar to Figure l, but showing an alternative form ofconstruction. 4 Figure 3 is an isometric view of a section of a tubesuch as disclosed in Figure 2.

In the form shown in Figure 1 there is a glass tube ill, such as iscommonly used for this purpose, and it is shown located in front of aback-- ing board it, which may be of any desired construction. On therear of the tubethere is shown a reflecting layer l2 and an absorbinglayer 83. The reflecting layer is generally white,

although it may be colored or tinted in any desired manner to accordwith the tint of light which is desired, where such tinting of thereflector is found helpful. The layer i3 is ordinarily black, althoughgood absorptive material of another color might be employed.

The preferable construction of these layers is to make them of a coatingmaterial which may be baked in place on the surface of the glass, andwill withstand the radiations and emanations from the tube. One suitablecoating material comprises resins, commonly referred to as glyp- 5 talor alkyd, with fatty acid dissolved in coal tar hydrocarbons or othersuitable solvents, such as hydrogenated naptha, petroleum naptha, andvarious combinations of them. The resins are condensation productsformed by the combining of polyhydric alcohol with dibasic acid. For thewhite layer, titanum oxide has been found particularly suitable,although other suitable pigments maybe employed for coloring thereflecting layer, and any suitable pigment, pref- 1 erably black, may beemployed in the absorptive layer. r

A convenient way of making the tube is to paint the coatings thereon andthereafter bake them on during the customary bombardment of the tube, atwhich time suflicient heat is generated to produce the necessary bakingof the coating. This has the advantage of producing the coated tubemerely by coatingit with the proper materials at. the proper timewithout requiring 25 any separate baking operation.

A coating of the material suggested has been found suitably resistantand durable under the normal conditions of use of such a tube, althoughit will be understood that the broader scope of so the invention is notdependent upon the particular coating material employed.

In the construction shown in Figures 2 and 3 the front half IQ of thetube is of clear glass similar to that employed in tube l0, but the rear35 portion or the tube is formed of two layers of glass, an inner whitelayer l5 and an outer black layer it. While the colors white and blackare preferred for the reflecting layer I5 and absorptive layer i6,respectively, it will be understood that other colors are permissible asindicated in connection with the description of layers 12 and I3, Abacking board Ha, similar to backing board i i, is indicated on thedrawing.

In making a tube such as shown in Figures 2 4 V 3 may operate verysatisfactorily, it will obviously involve more expense in itsmanufacture than will the simple coating of the tube during thebombardment step, as discussed in connection with Figure 1, and whileother suitable resistant materials may be employed in place of thosesuggested for use in coatings I2 and I3, it must be understood thatordinary paints and varnishes are aflected by the radiations andemanations from the tube to such an extent that their useful life isbrief. Accordingly, if materials are used in place of those suggested,care must be taken to select those which will withstand the conditionsto. which they are subjected in use on such a tube. The use of thereflective and absorptive coats, as described above, has a number ofimportant ad-- vantages. Of course, it is readily understood that byreflection of the light towards the front, the waste of the light, whichwould otherwise occur, is avoided. It may not so readily appear that theapparent breadth of the tube is approximately doubled, but this will beunderstood if it is taken into consideration that the light directlytransmitted results in an apparent column of light which is smaller thanthe actual column of gas, while the use of the reflector results inlight being so directed that the entire tube to thelighting up of 'theback board is avoided, the

sign stands out against the relatively dark background and isadditionally distinct because of this reason. As a consequence tubesbecome :much more clearly and readily visible and at the same time theform, into which the tubes are bent so as to make the desired charactersor designs, is much more clear cut and distinct. A small tube thuscoated is as clearly visible as one -about three times the capacitywithout the coat- Having set forth the principles of this invention anddisclosed two specific forms thereof, it will be understood that thespecific disclosures are by way of illustration and the appended claimsare not limited thereby, except so far as stated in the claims It willbefurther under- 5 stood that whereas for the sake of brevity referenceis made in the claims to a neon tube, this expression is intended tocover a tube of this type regardless of the particular-gas employedwhether neon, argon, krypton, or other gases or 1 vapours that may beused in a like manner, or a mixture of such gases, reference being madeto the type of light rather than to the particular gas employed.

1 What I claim is:

' 1. A neon tube having a reflecting coat around its rear half, saidcoat having incorporated therein titanium oxide.

2. A neon tube coated on its rear sidewith a composition comprising aresinous condensation 20 product formed from polyhydric alcohol anddibasic acid and dissolved in a suitable solvent, baked in place uponthe tube, and containing a suitable pigment. 1

3. A tube in accordance with claim 2 and in 25 which the pigmentcomprises titanium oxide.

4. A tube in accordance with claim 2, and the coat containing whitepigment next to the glass and black pigment in its outer portion.

5. The method of making a coated neon tube, 0 I

which comprises coating a portion of the tube with a suitable reflectiveenamel composition and baking the enamel ontothe tube duringthebombardment of the tube in the process of making the same. 5-

as a pigment.

' ALLEN P. TALLMAN.

